Prove that the sum of two consecutive odd primes has at least three prime divisors (not necessarily different).
Asked
Active
Viewed 3,496 times
1 Answers
10
Well, if $P$ and $Q$ are consecutive odd primes, then $P+Q$ is even, so $2$ divides $P+Q$. Hence, $P+Q=2R$, for some $R$. If $R$ were prime, then $R$ were a prime between $Q$ and $P$, a contradiction.
mathse
- 2,438
- 12
- 18